A decade of the sharing economy: Concepts, users, business and governance perspectives

Sharing economy platforms have been transforming production and consumption systems in cities around the world. While the sharing economy may contribute to addressing sustainability issues, its actual economic, social and environmental impacts remain poorly understood. Advancing more sustainably promising forms of sharing and leveraging its benefits, while circumventing its pitfalls, is becoming increasingly important in the era of Covid-19 and climate crisis, economic downturn and uncertainty, and loss of social connectedness, particularly in anonymous urban environments. The ways to capitalise on strengths of the sharing economy are still poorly understood. In particular, the roles and perspectives of users, businesses and municipal governments in institutionalising the sharing economy in various geographical contexts are essential to examine. This volume seeks to advance the research field by focusing on four research areas: 1) understanding the sharing economy conceptually; 2) user perspectives on the sharing economy; 3) business perspective on the sharing economy; and 4) urban governance perspective on the sharing economy. The twenty articles in this volume discuss sustainability implications of the sharing economy from different perspectives, in various geographical contexts, and drawing on a range of disciplines. The volume makes a significant contribution by bringing in empirical findings from emerging and developing economies, including Brazil, China, Indonesia, Poland, the Philippines, South Korea, Thailand and Vietnam, thereby supplementing more frequently discussed perspectives from high-income countries. The volume also outlines the course for future research.

organisational models that are transforming marketplaces and cityscapes, where goods and services, skills and spaces are shared, exchanged, rented or leased. Although sharing among families and friends has been a traditional form of exchange throughout human history (Belk, 2010), new forms of sharing between strangers enabled by digital technologies are emerging (Frenken and Schor, 2017). The sharing economy phenomenon has been growing for over a decade (Acquier et al., 2017;Frenken and Schor, 2017;Zvolska et al., 2019). Particularly spurred by the rapid digitalisation and penetration of smart phones, sharing economy platforms have been transforming production and consumption systems in cities around the world (May et al., 2017;McLaren and Agyeman, 2015;Zvolska et al., 2018). The sharing economy is forecast to grow by more than 25% annually (PwC, 2014).
At the same time, the sharing economy is a contested concept (Cohen, 2016;Schor, 2014;Sundararajan, 2016). One argument is that the sharing economy has potential to reduce environmental impact by putting underutilised assets to work, strengthen social cohesion by connecting individuals via ubiquitous digital technology, and stimulate entrepreneurship (Botsman and Rogers, 2011;WEF, 2017). Proponents of the sharing economy claim that it can help mitigate new realities of continuing economic recession, governmental austerity, increasing disparities between 'haves and have-nots', and growing environmental problems caused by consumption (Agyeman et al., 2013;Botsman and Rogers, 2011;Gansky, 2012). Many sharing organisations also frame their visions and operations in sustainability terms (Voytenko Palgan et al., 2017).
However, there is growing criticism of the sharing economy and its effects. Critical voices warn that there is little evidence to support sustainability claims of sharing (Cohen, 2016;Schor, 2014). The sharing economy is seen as a threat to professionalism, public safety, privacy and health, and labour rights (SOU, 2017;Vith et al., 2019), as well as a risk of promoting increased consumption and associated environmental burden (Martin, 2016;Voytenko Palgan et al., 2017). In particular, the rapid penetration of services delivered by multi-national platform giants such as Airbnb and Uber has been taking governments by surprise, leaving them unprepared for the challenges that might arise (Davidson and Infranca, 2016;Ferreri and Sanyal, 2018;Finck and Ranchord as, 2016;Gy odi, 2019;Voytenko Palgan et al., 2017). As a result, many national and local governments have now started regulating sharing economy practices .
While the sharing economy contributes to both creating and addressing sustainability issues, the actual economic, social and environmental impacts of the sharing economy remain poorly understood. Advancing more sustainably promising forms of sharing and leveraging its benefits, while circumventing the pitfalls of the sharing economy, is becoming increasingly important in the era of Covid-19 and climate crisis, economic uncertainty and loss of social connectedness, particularly in anonymous urban environments. The ways to achieve this are not yet understood. In particular, the roles and perspectives of users, businesses and municipal governments in institutionalising the sharing economy in various geographical contexts are important to examine. This volume therefore aims to explore the diverse sustainability claims of the sharing economy, i.e. its economic, environmental and social implications, and the institutionalisation pathways of new sharing forms in different socio-cultural contexts. The volume seeks to contribute to advancing the research field by exploring these issues, focusing on four principal areas of research: Understanding the sharing economy; User perspectives on the sharing economy; Business perspective on the sharing economy; Urban governance perspective on the sharing economy.
The sharing economy remains a contested phenomenon lacking a definitional precision. There is no common understanding of the sharing economy (Curtis and Lehner, 2019;Ertz and Leblanc-Proulx, 2018;Gur au and Ranchhod, 2020), and various terms are used, e.g. collaborative consumption, access-based consumption, collaborative or peer economy. A comprehensive framework is needed to design studies that are comparable. However, before arriving at a commonly agreed definition, a thorough analysis of different concepts, theories and understandings of the term 'sharing economy' is needed.
The sharing economy research field is split between various streams of research, such as reputation systems, taxation and regulation issues, trust, or conceptual foundations. There is a need to address the evolution of the research field, analyse how it has developed, and characterise the relationships between various sharing economy domains (Ertz and Leblanc-Proulx, 2018). Many of the challenges of understanding the sharing economy are linked to the fragmented research on the topic, using either secondary or primary data, so a mixed-method approach exploring structural and functional units of the sharing economy is needed (Gur au and Ranchhod, 2020). As most of the research is being conducted in the Global North, there is also a need to understand how, in what form, and with what implications the sharing economy is emerging in the developing world (Yuana et al., 2019).
Previous research on the users' perspectives on the sharing economy has highlighted motivations of users to participate in various forms of sharing economy schemes (Bardhi and Eckhardt, 2012;Moeller and Wittkowski, 2010;M€ ohlmann, 2015;Tussyadiah, 2015), demographics of users (c.f. Martin et al., 2010;Owyang et al., 2014), as well as the inclusionary and exclusionary effects by and on users (Schor et al., 2016). Several studies have also highlighted the shifting role of the citizen-consumers in the sharing economy e from the more passive consumer, i.e. citizen buying a product or service from a company (business-to-consumer or B2C), to a dual role as both provider and receiver in a peer-to-peer (P2P) relationship (Eden, 2015;Jaeger-Erben et al., 2015). Hence, the term 'user' is often applied in the sharing economy discourse in order to denote the dual peer relation. While there are several studies on the motivations and perceptions of active users of the sharing economy, less is known about the wider public perceptions of the sharing economy (Cherry and Pidgeon, 2018) and of the perspectives of non-users, e.g. why the current sharing economy may not be available or appealing to them. As pointed out by Retamal (2019) in this volume, existing research on sharing economy practices has focused on high-income countries, while considerably less attention has been given to sharing economy practices in low-income parts of the world.
Although research on business models has exploded in recent years, understanding how value is created, delivered and captured in business models in the sharing economy remains in a nascent stage (Andreassen et al., 2018). Research is emerging on business model innovation at organisational level (Bocken et al., 2013) and on innovating sustainable business models (Breuer et al., 2018;Geissdoerfer et al., 2016;Joyce and Paquin, 2016;Yang et al., 2017), but consensus is limited on definition of sharing business models, their fundamental characteristics, and the nature of markets they create. We also know very little about why sharing organisations diversify their business models, what mechanisms for diversification are, and how and why they create business model portfolios. Assessment of viability and sustainability of different sharing economy business models is lacking. Tools and methods for business modelling are still scarce, and those that exist rarely elevate sustainability as a driver or an explicit goal when business models in the sharing economy are being developed (Geissdoerfer et al., 2018). Examples of successful sustainable business model implementation are also rare (Ritala et al., 2018), and there is the 'designimplementation gap' (Baldassarre et al., 2020;Geissdoerfer et al., 2018). Knowledge is also scarce on the mechanisms for mainstreaming and upscaling different business models, and sharing business models in particular (Meijer et al., 2019). The understanding is emerging that professionalisation and commercialisation of originally communal forms of sharing might have implications for their sustainability ambitions, but empirical evidence is lacking (Cockayne, 2016). The interplay between business model innovations and socio-technical and organisational contexts overall has not been sufficiently explored (Grinevich and Huber, 2015). Indeed, sharing organisations do not evolve in isolation. They affect the established sectors and companies, which are responding by either joining the sharing economy organisational field to reap economic benefits or tackling the disrupting newcomers (Winterhalter et al., 2015). How the changes in business models of incumbents affect the sharing economy is largely unknown (Ciulli and Kolk, 2019).
Various aspects of urban governance of the sharing economy require further attention (Bernardi and Diamantini, 2018;Ma et al., 2018;Voytenko Palgan et al., 2019). Sharing in cities is promising because of high density and high levels of income of urban population, which leads to high levels of consumption and results in high volumes of underutilised assets. The rapid digitalisation also increases connectivity between sharing platform users. There is a need to understand the role of policy and regulation in enabling or constraining the sharing economy, as well as the kind of governance arrangements needed to ensure socio-economic and environmental sustainability of the sharing economy in cities. While municipalities engage with sharing economy organisations differently Zvolska et al., 2018) and govern the phenomenon in proactive or reactive ways (Bernardi and Diamantini, 2018;Davidson and Infranca, 2016;Finck and Ranchord as, 2016), municipal institutional responses to the sharing economy remain underdeveloped (Ma et al., 2018). At the same time, urban governance of the sharing economy is becoming increasingly important since, if managed well, the sharing economy may have a transformative impact on cities and their economic prosperity, social viability and environmental quality (WEF, 2017). Therefore, it is important to understand how to govern the sharing economy in cities so that municipalities and their residents could capitalise on the benefits offered by the sharing economy and circumvent its pitfalls.
This special volume brings together articles from different disciplines that offer conceptual insights and bring forward empirical data illustrating how the sharing economy and its sustainability implications can be understood. The articles also show how more promising forms of sharing can be advanced by the users of sharing economy platforms, the platforms themselves, incumbent businesses, and municipalities. The sharing economy phenomenon has penetrated the academic and policy discourse on sustainable consumption and production e a general topic on which the Journal of Cleaner Production is publishing extensively. This volume continues the series of Special Volumes on Sustainable Consumption and Production and on Product-service Systems.

This special volume at a glance
This volume emerges from paper sessions at the 4th International Workshop on the Sharing Economy (4IWSE) held in Lund, Sweden, on 15e16 June 2017, and several additional contributions.
During the workshop sessions, conceptual, methodological and empirical questions on the operations, governance aspects, actors and impacts of the sharing economy in different geographical contexts were explored. The workshop was testimony to a growing interest in seeking to understand the socio-economic and environmental dimensions of the sharing economy that engages various actors, including sharing economy platforms, their users, incumbent businesses, and municipal governments.
The twenty articles in this volume address sustainability implications of the sharing economy from different perspectives, i.e. conceptual, business, consumer and governance. They bring insights from different countries, including Austria, Brazil, China, Germany, France, Indonesia, Italy, the Netherlands, Poland, the Philippines, South Korea, Spain, Thailand, Vietnam, and the United Kingdom. The volume therefore makes an important contribution by bringing in empirical findings from emerging and developing economies to supplement the more frequently discussed perspectives from high-income countries. Furthermore, the articles draw on different conceptual and theoretical backgrounds, stemming from a range of academic disciplines, e.g. Business and Management, Geography, Economics, Environmental Sciences, Sociology, Political Science, Psychology, Science and Technology Studies, and Urban Studies.
The first three articles help to improve understanding of the sharing (Gur au and Ranchhod, 2020) and collaborative (Ertz and Leblanc-Proulx, 2018) economy concepts and their evolution, and how the sharing economy manifests itself in the case of ridesharing in the Philippines and Indonesia (Yuana et al., 2019). The next seven articles focus on consumer, resident and citizen perspectives, including their perceptions, motivations (Cerutti et al., 2019;Hartl et al., 2018;Hawlitschek et al., 2018;Schanes and Stagl, 2019) and acceptance of sharing services (Cherry and Pidgeon, 2018), and the role of sustainability for consumers of the sharing economy (Cherry and Pidgeon, 2018;Hartl et al., 2018;Laamanen et al., 2018;Retamal, 2019). This is followed by seven articles discussing business perspectives on the sharing economy, including sharing economy platforms (Curtis and Mont, 2020;Fraanje and Spaargaren, 2019;Geissinger et al., 2019;Guyader and Piscicelli, 2019;Netter et al., 2019;van Waes et al., 2018) and incumbents (Ciulli and Kolk, 2019). The final three articles discuss the relevance of the sharing economy in cities, its impacts and challenges (Bernardi and Diamantini, 2018;Gy odi, 2019;Ma et al., 2018), and the ways in which the sharing economy may be governed in urban contexts (Bernardi and Diamantini, 2018;Ma et al., 2018). In subsections 2.2-2.5, we discuss article contributions in detail.

Understanding the sharing economy
Given the complexity of the phenomenon of the sharing economy, a variety of methods and approaches are necessary to study the phenomenon from various perspectives. The articles in this volume bring together an interesting mix of concepts, theory and methods. Gur au and Ranchhod (2020) address the numerous attempts to understand the sharing economy, by analysing how the concept is understood in the literature and by different stakeholders. Ertz and Leblanc-Proulx (2018) explore how the sharing economy field has evolved by employing bibliometric analysis. Special attention is paid to how previous literature has discussed whether the sharing economy is sustainable. Zooming in from the broader understanding of the sharing economy to its specific sectors, the paper by Yuana et al. (2019) studies ridesharing in Indonesia and the Philippines. The authors explore the framings of ridesharing found in local news articles to bring a perspective from the Global South. The three studies offer a deeper understanding of complex structure and dynamics of the sharing economy's and result in theoretical, methodological and practical implications.
Gur au and Ranchhod (2020) explore the structural and functional aspects of the sharing economy by focusing on its defining characteristics, main stakeholders, and systemic benefits and challenges. They draw on the perspective of a complex dynamic system, using interpretative content analysis. Using NVIVO, they analyse secondary sources and 256 interviews with sellers, service providers, clients or traditional competitors in France, Italy and the UK, bringing a rich dataset to this special volume. They deliver insights on who the main stakeholders are, how the sharing economy is understood and what the benefits and challenges are, as perceived in the literature and by the stakeholders. They find that the peer-to-peer dimension is much more emphasised in academic articles, books, and business reports compared to articles in newspapers and social media blogs. Books and service providers mainly focus on the benefits of the sharing economy, while competitors highlight the challenges. Academic and newspaper articles, as well as the general public, provide a more balanced view.
Similar to Gur au and Ranchhod (2020), Ertz and Leblanc-Proulx (2018) examine how the sharing economy is understood and depicted in the literature. They explore how the collaborative economy evolved in the past years and with it the sustainability discussion around it. The authors employ three levels of analysis: bibliometric analysis; network analysis to identify prominent authors, leading publications, and extant and upcoming research clusters; and content analysis to identify main research questions. Searching for title, abstract and keywords of articles in Web of Science and Scopus databases, their study shows interesting insights into, for example, who are the most influential authors, publications or institutions. The authors also use techniques for data mapping to illustrate the progression of publications in the sharing economy literature over the past decade. Yuana et al. (2019) employ frame analysis to study how ridesharing is framed in the news content in Indonesia and the Philippines, and how this reflects the policy response to ridesharing. The authors first identify five frames: commuter solution, unregulated passenger transport services, cooperative business, nonconformity solution, and informal livelihoods. They elaborate on whether the frames constitute a problem, a solution, or a rationale. Then the authors link the identified frames to policy responses to ridesharing. In the Philippines, legal sanctions are being imposed after establishing ridesharing as a new legal category. In contrast, Indonesia is regulating ridesharing under an existing legal category, which provides a more balanced position between key stakeholders.

User perspective on the sharing economy
A number of papers in this volume contribute to knowledge on why users engage in sharing practices and their experiences (Cerutti et al., 2019;Hartl et al., 2018;Hawlitschek et al., 2018;Schanes and Stagl, 2019). Hawlitscheck et al. (2018) show that consumer motivations to engage in peer-to-peer sharing include cost-saving, trust in other users, ecological sustainability, and a "modern lifestyle", and factors that impede peer-to-peer sharing include the independence of private ownership, effort expectancy, and perceived process risks. Hartl et al. (2018) have studied motivations of both B2C and P2P car sharing, and specifically explored the role of sustainability in the promotion of these services. The study shows that environmental concerns play an important role, particularly for those choosing P2P car sharing over B2C. However, for those choosing B2C services, the financial benefits and convenience are considered more important. Here, environmental impacts are considered more as a positive side effect. These results indicate the importance of distinguishing between P2P and B2C services in marketing, communication strategies, and public policy. As pointed out by Hawlitscheck et al. (2018), this also suggests that it is important to be wary of greenwashing in the promotion of sharing economy services. Schanes and Stagl (2019) have explored the motivations of food sharing practitioners in an Austrian context. In contrast to the transport sharing cases (Cerutti et al., 2019;Hartl et al., 2018), the motivations here concern "emotions and morality" and "identity and sense of community", but there are also 'instrumental' motivations, such as getting access to free food. The authors show that the diverse agendas of food sharers e from political systemic change to simply getting access to free food e seem capable of coexistence and at times be reinforced. Cerutti et al. (2019) have studied the motivations and user perceptions of bike-sharing services in the context of a mid-sized Brazilian city. Their study shows that the main motivation is "health and environment", followed by being a role model and associated with a positive lifestyle. Their study also includes the perceptions of non-users, primarily women, who reported that the cycling infrastructure of the city is not perceived as convenient and safe enough and that cycling does not match their lifestyle. Cerutti et al. (2019) conclude that these findings indicate the importance of including citizen participation in the development of smart city strategies e smart digital solutions will not be enough, if the perspectives of users and non-users are not considered.
Two papers in this volume specifically contribute with knowledge on factors for mainstreaming of sharing economy practices. They do so by exploring the perspectives of the broader public, thereby going beyond studies of active users. Cherry and Pidgeon (2018) explore broader public perceptions of the sharing economy, desires, and concerns regarding mainstreaming of the sharing economy. The study shows that the overall perceptions of the sharing economy in the UK context are positive, specifically in terms of the potentials to reduce environmental footprints, strengthen community, and enable access to previously unaffordable products and services. However, the results also indicate more deep-seated concerns about the (lack of) safety and hygiene of shared products and peer-delivered services, fear of social inequality, and general low levels of trust in companies used for sharing operations. The conclusion is that these are factors that need to be dealt with if the sharing economy is to be mainstreamed.
The bulk of research on the sharing economy has been conducted in the Global North, often in contexts saturated with consumer goods and where individual ownership of items like cars or laundry machines has been the norm. Retamal (2019) contributes by exploring collaborative consumption practices in the context of Southeast Asia, more specifically Bangkok, Manila and Hanoi, where private ownership of such products is less common. The case studies include not only active users of collaborative consumption services but also policy makers, business owners, consultants, and NGOs, in order to explore prospects for mainstreaming. Retamal (2019) concludes that there are several factors that indicate possibilities for mainstreaming of collaborative consumption, e.g. high density of people, limited housing sizes, traffic congestion, and long commuting times. However, the study also shows that there is resistance, particularly to shared-access practices such as shared laundry machines or car sharing. The resistance stems from lack of trust, lack of knowledge of how to use the shared equipment, and lack of institutional support for consumer-to-consumer business models.
Lastly, Laamanen et al. (2018) contributes by highlighting nonmonetary dimensions of the sharing economy, and time-banking specifically. Drawing on Karl Polanyi's conceptualisation of house holding, the authors argue that time-banking contributes to self-sufficiency and autonomy by connecting people beyond kin relations. They argue that such forms of non-monetary sharing need to be emphasised to challenge the neoliberal forms of the sharing economy, where reproductive work is being commercialised through platforms.

Business perspective on the sharing economy
The articles that focus on business models and practices in the sharing economy span a range of topics. These comprise business model innovation and implementation (Curtis and Mont, 2020), the communal-commercial continuum of SEBMs (Netter et al., 2019), upscaling and development trajectories (Fraanje and Spaargaren, 2019;van Waes et al., 2018), sustainability connotations (Geissinger et al., 2019), the role of incumbents in affecting the landscape of the sharing economy (Ciulli and Kolk, 2019) and finally, the role of emotions and human agency in the dynamic interaction between companies, practices, and practitioners that shape the future trajectories of the sharing economy (Fraanje and Spaargaren, 2019).
Addressing the business perspective are conceptual articles (Curtis and Mont, 2020;Netter et al., 2019), articles based on extensive and longitudinal empirical research (Guyader and Piscicelli, 2019), and articles that combine conceptual and empirical sides. The articles present case studies (Fraanje and Spaargaren, 2019;Guyader and Piscicelli, 2019) and cross-case comparisons (van Waes et al., 2018), and delve deeply into individual organisations, with a bird's-eye perspective on specific aspects of the sharing economy (Geissinger et al., 2019). Contributions explore peer-to-peer sharing organisations and business-to-consumer organisations (Netter et al., 2019;van Waes et al., 2018). We learn about sharing organisations from the mobility sector, including bikes (van Waes et al., 2018) and car sharing organisations (Guyader and Piscicelli, 2019), sharing of physical assets (Guyader and Piscicelli, 2019) and the entire spectrum of other sharing business models (Geissinger et al., 2019).
van Waes et al. (2018) develop a transition framework aimed at improving understanding about evolution of different SEBMs and especially mechanisms supporting and hindering upscaling, in different socio-technical contexts. The framework identifies "actors (individuals, firms, organisations), institutions (regulations, norms, beliefs) and material artefacts and infrastructure" as critical elements in understanding upscaling. It is applied to the bike sharing sector where mechanisms of upscaling of four business models e two-way station-based, one-way station-based, one-way free floating, and peer-to-peer sharing e are discussed and tested. The findings show that more traditional station-based business models have already been institutionalised, but experience difficulties with scaling up. On the other hand, the novel one-way free-floating models have the highest scaling potential. By combining the business model perspective with transition analysis, the framework can be used to predict the upscaling potential of different SEBMs. The paper contributes to transition and institutionalisation literature.
Ciulli and Kolk (2019) explore the role of incumbents in the sharing economy, and how their own sustainability profiles, including economic, environmental, and social value creation are affected. The authors develop a typology of business model innovation for sharing, and bring in cases of incumbents' entry in the sharing economy. They discuss the sustainability implications of each type of business model innovation employed by incumbents. Then sustainability benefits and drawbacks of incumbents' entering the sharing economy are explored, both for the incumbents themselves and for the development of the sharing economy. The paper advances the literature on the sharing economy and sustainable business models.
The sharing economy as a research field is still in an emerging state, lacking a solid conceptual foundation (Acquier et al., 2017). A contribution to theory-building on SEBMs and the markets they serve is the paper by Netter et al. (2019), where a theory-driven framework is developed for describing and analysing business-toconsumer and peer-to-peer sharing models drawing on the literature on partial organisation. The authors explore the importance of five core dimensions of organising (membership, hierarchy, rules, monitoring, and sanctions), and employ them to understand and map the continuum between largely communal (user-driven) and commercial (platform-driven) SEBMs. The intention is to offer a tool that allows description and analysis of SEBMs "without indulging in speculations about strategic intent and normative ideals of what sharing should be" (Netter et al., 2019). Geissinger et al. (2019) address another underexplored issue, namely the emergent tendency of sharing organisations to shed their sustainability aspirations when they upscale or become mainstream. The authors seek evidence of that by studying sustainability connotations of 121 platforms collected through social media analysis. The findings demonstrate that sustainability connotations are diverse, but specific for various sharing sectors, such as fashion, on-demand services, and logistics (Geissinger et al., 2019). At the same time, the research found no evidence of the sharing economy unicorns describing themselves as being sustainable. The platform level analysis shows that sustainability credentials are becoming less prominent in marketing and communication compared to earlier discussions of the sharing economy per se and its sustainability potential. The authors discuss the development "from accessing and sharing to acquiring and consuming" as representing evolution of sharing organisations rather than the general development in the sharing economy landscape. They propose that it is unlikely that the sharing economy will drive sustainability discourse and action in the future, but that sharing organisations will rather adjust to a legal framework that governs diverse sectors of which different sharing sectors will be part. Guyader and Piscicelli (2019) address yet another interesting and emerging phenomenon in the sharing economy organisational field, namely business model diversification. This follows the recent trend among the sharing organisations to develop multiple business models for different sets of customers. The authors set out to test a proposition that "successful business model configurations maximise the existing resources of a firm to establish hard-toimitate capabilities and create sustainable competitive advantage". Focusing on the sharing mobility start-up GoMore, the article traces its evolution and diversification. It started as a non-profit ridesharing website and developed into a for-profit platform that provides both peer-to-peer and business-to-consumer mobility services. The authors identified six key resources comprising business model portfolio, i.e. member community, platform technology, user data, customer support, local management teams, and partners. Also three key capabilities were defined, including leverage of the community's assets, technological improvement, and user engagement. The key resources and capabilities are shared among the business models and geographical contexts with the aim to improve the quality of the offer, facilitate growth, and improve profits (Guyader and Piscicelli, 2019). The article integrates the strategy literature on business models with the marketing literature on the sharing economy.
The article by Curtis and Mont (2020) aims to fill the designimplementation gap identified in literature by developing the sharing economy business modelling tool for sustainability. Unlike the paper by Netter et al. (2019), which distances itself from any "strategic and normative" stance, Curtis and Mont (2020) take a normative perspective, suggesting that SEBMs need to be deliberately designed with sustainability in mind, since accessing and utilising idling capacity via platforms has sustainability benefits, but reaping these benefits is not automatic. The authors develop a tool aimed at this. The tool is based on performing a morphological analysis of SEBMs, according to which business model attributes and their alternate conditions are systematically mapped. Curtis and Mont (2020) propose four conditions for improved sustainability performance: SEBMs operating as platforms, leveraging idling capacity of an existing stock of goods, applying non-pecuniary motivation for ownership, and facilitating temporary access over ownership. The sharing economy business modelling tool has been developed and tested with experts, and should be of interest to all actors concerned about sustainability impacts of sharing organisations.
The article by Fraanje and Spaargaren (2019) has its starting point in observation that the sharing economy "increasingly follows a conventional market rationality of payments and profits" in contrast to its initial social and societal aspirations. The authors set out to investigate present and future trajectories of sharing practices on the Peerby and MyWheels platforms, by employing a practice theoretical perspective of social change addressed in the sociological theories (Schatzki, 2016). The article demonstrates that participants in the sharing economy engage with sharing practices in both pragmatic and emotional ways. The findings also show the important role of emotions and human agency in influencing the dynamic interactions between companies, practices, and practitioners that shape the future of the sharing economy. Analysing the practices of two platforms, tool and car sharing (Peerby and MyWheels respectively), two distinct trajectories are identified. While Peerby from the outset is based on the idea of sharing goods by connecting people, its introduction of Peerby Go seeks to increase efficiency of sharing at the expense of reduced social interaction. In contrast, MyWheels, whose initial aim was to optimise car sharing efficiency, is currently trying to increase the sense of community on the platform. The authors suggest that, in order to understand trajectories of sharing practices, we need to consider how sharing organisations organise their practices, the types of products that are shared, and how people embed sharing practices in their daily lives (Fraanje and Spaargaren, 2019). This practicetheoretical perspective on the future of the sharing economy resonates with the call to study sharing practices of resource owners, resource users, and platforms in the article by Curtis and Mont (2020).

Urban governance perspective on the sharing economy
The articles focusing on the urban governance perspective on the sharing economy have a broad geographical coverage, as they build on the case studies of sharing economy developments and urban governance in eight global cities. While the article by Gy odi (2019) has a narrower focus on evaluating socio-economic impact of Airbnb on local residents and the hotel industry in four cities of Paris, Barcelona, Berlin and Warsaw, articles by Bernardi and Diamantini (2018) and Ma et al. (2018) focus on how the sharing economy may be governed in cities to advance its sustainability potential primarily in socio-environmental terms. Bernardi and Diamantini (2018) apply the sharing concept and the collaborative urban governance perspective to explore how local authorities can build "a real sharing city". The authors develop a conceptual model comprising three dimensions of the sharing city, i.e. technological, economic and human, to analyse urban governance of the sharing economy in Seoul and Milan. They find that, while specific municipal governance approaches differ, both municipalities work along all three dimensions to create a sharing city. The cities of Seoul and Milan view human dimension and social capital as important, so avoid building on purely neoliberal logic of developing prosperous and competitive urban areas or on a more technocratic orientation of smart cities. The authors argue that it is important to recognise the role if new actors in urban governance and promote their cooperation, as well as for municipalities to act as enabling states of the sharing paradigm. They find, however, that both municipalities lack institutionalised mechanisms of collaboration (Bernardi and Diamantini, 2018).
Like Bernardi and Diamantini (2018), Ma et al. (2018) argue that collaborative governance of the sharing economy in cities is important, to deliver its socio-environmental sustainability. They develop an analytical framework comprising principled engagement, shared motivation and capacity for joint action to explore collaborative governance processes surrounding the development of free-floating bike sharing in Shanghai (Ma et al., 2018). The authors find that lacking recognition and integration of user groups and other social actors in the governance process is one of the main hindering factors for a well-functioning collaboration between business, government and the society at large. They suggest that municipalities should be more proactive "to accommodate, nurture and integrate emerging social actors as governance partners in the sharing economy", which in turn would advance social and environmental potential of sharing economy initiatives (Ma et al., 2018, p. 396). The authors propose an alternative model that engages society in governing the sharing economy.
The article by Gy odi (2019) takes a step back to examine the impacts of Airbnb on European cities, their residents and the hotel industry, and therefore contributes with knowledge that can be used by policy-makers, urban planners and other relevant actors in governing the operations of short-term home rentals. The author uses a web-scraped dataset of Airbnb listings in Paris, Barcelona, Berlin and Warsaw to show that listings from professionalised hosts dominate in all cities, while 'real' sharing economy (Frenken and Schor, 2017) listings constitute between 49.5% (Berlin) and 11.1% (Warsaw). The author argues that this reduces the stock of properties for local inhabitants and leads to eventual gentrification. At the same time, the study identifies governance approaches of city councils to be the reason for the variation (Gy odi, 2019). Another finding from the spatial analysis is that "while Airbnb was highly concentrated in areas dense with traditional hotels, it complemented the hotel industry in more suburban areas" (Gy odi, 2019, p. 546). This also proves that Airbnb exacerbates pressure from tourism in the case study cities.

Conclusions and future research
This section summarises the key contributions to knowledge made by the articles in this volume, and concludes by suggesting areas for future research.

Conclusions
This volume discusses sustainability implications of the sharing economy from different perspectives, in various geographical contexts, and drawing on a range of disciplines. It makes an important contribution by bringing in empirical findings from emerging and developing economies, including Brazil, China, Indonesia, Poland, the Philippines, South Korea, Thailand and Vietnam, thereby supplementing more frequently discussed perspectives from high-income countries.
The articles in this volume have contributed to a better understanding of the sharing economy phenomenon in several ways. They explored the evolution of the sharing economy as a research field, mapping the most influential authors and publications, which provided an interesting overview of the existing literature. They also brought new insights into the narratives and policies of the sharing economy in the Global South by analysing ridesharing in the Philippines and Indonesia. They contributed methodologically by using both secondary and primary sources to define the main characteristics of the sharing economy, its stakeholders, and the perceived systemic benefits and challenges. Finally, the papers debated the importance of sustainability in the literature and in practice, which is likely to play a major role in future publications.
From the user perspective, it can be concluded that there is plenty of research on user motivations, particularly emphasising the perceived benefits to users, in terms of cost-saving, health, and being a role model, but also the impediments to users. The perspectives of non-users have also been explored, as well as how the wider public perceives the sharing economy and the potential of the sharing economy for mainstreaming. However, the task remains for researchers to explore the risks that are not so easily perceived for users and the wider public in the short-term, such as risks related to data integrity, increasing reliance on a few digital giants, and lock-ins.
One important finding from the business perspective is that the sharing economy is not sustainable by default. Studies in this volume discuss many positive and negative sides of the sharing economy and how perceptions, actions and connotations about the sharing economy are changing with time. There is an emerging trend that some organisations shed their sustainability aspirations as they grow to fit the mainstream institutional contexts. Therefore, some studies call for a more strategic and deliberate stance on how sharing economy business models are shaped and evolve. Some studies suggest that it is important to understand the roles and interplay between actors, institutions and infrastructures that shape the evolution, sustainability and upscaling of business models in the sharing economy. Several papers conclude that understanding sharing practices of different actors, such as resource owners and resource users, is also critical, because they affect the sustainability of sharing organisations and trajectories of their development.
From the urban perspective, it is clear that the governance approaches of the sharing economy vary between geographical contexts. These are primarily dependent on sustainability challenges that various cities are facing, as well as the goals that they are pursuing. While the articles revealed both reactive and proactive engagement with the sharing economy among municipal governments, one important conclusion is that more agile action by municipalities will be important to leverage the sustainability potential of the sharing economy. In particular, collaboration was argued to be useful when governing the complexity of sharing economy developments, but to make it work, more focus should be paid to a better integration of emerging social actors in the governance processes and building on the social capital of urban residents.
As a whole, the articles in this volume represent an ongoing discussion on sustainability implications of the sharing economy and on the ways to leverage its economic, social and environmental potential while mitigating its risks. For this to happen, municipalities, communities, sharing economy platforms, incumbent businesses and knowledge institutes need to steer towards more sustainable development of the sharing economy to address the issues that are relevant to their particular contexts and concerns.

Future research
The articles in this volume give an indication of the course of future research.
From the perspective of understanding and conceptualising the sharing economy phenomenon, placing and exploring the sharing economy in the sustainability context remains an important area of current and future research. A more rigorous theoretical modelling of the sharing economy, drawing on existing economic and market theories, is also identified as important. In the context of the Global South, it will be crucial to further explore the interplay between the sharing economy as a global phenomenon, national regulations and city-level law enforcement concerns.
From the user perspective, it is relevant to not only deepen the knowledge on motives and impediments of participating in or mainstreaming of the sharing economy but also to critically explore the power-relations in a growing B2C sharing economy, where citizens no longer own, manage or repair the products they use. This also means handing over certain forms of power, control of resources, skills and know-how to companies. Research on the sharing economy has almost exclusively focused on urban contexts in 'advanced economies', while sharing practices in rural, small town and 'less advanced' contexts have received far less attention. In future research, it would be of interest to explore perspectives, knowledge and practices of sharing in the peripheries, beyond the big platforms. Perhaps there are experiences here that could inform the steering of sharing economies towards increased user autonomy.
From the business perspective, there is a need to improve our understanding about business models in the sharing economy, including mechanisms of their diversification and ecosystems of sharing business models. Further research is needed on business model innovation in socio-technical contexts, studying actors, institutions and infrastructures in their interplay. Another important direction is to explore the role of incumbents in shaping the sharing economy by affecting actors, institutions and infrastructures. In order to utilise the sustainability potential of the sharing economy, tools and methods for evaluating sustainability performance of business models need to be developed. More importantly, it is critical to improve the granularity of assessment, which would allow us to understand how change in design of certain business model elements affects the overall sustainability of the sharing economy business model. Future research should also focus on improving understanding of how sharing organisations evolve, and why and when their sustainability aspirations change, including cross-case and cross-sectoral comparisons. Finally, research on sharing economy business models needs to be supplemented with studies about behaviour of sharing economy participants, i.e. individuals who are involved in the sharing economy either as resource owners and resource users, and their everyday practices, since they affect both the sustainability of sharing economy business models and trajectories of their upscaling and mainstreaming.
From the urban governance perspective, there is a need for a deeper analysis of the socio-cultural, historical and political context in which various cities are embedded, to improve understanding of how municipalities may govern the sharing economy. Following this, it would be important to develop the understanding on the types of governance approaches that municipalities may utilise to strengthen their position towards sharing economy organisations and find ways to co-exist or collaborate, benefiting cities and their residents. Further comparative case studies among diverse economic, social and cultural contexts can contribute to the conceptualisation of collaborative governance phenomenon especially in the context of upscaling the sharing economy.

Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.